The present invention relates to a flame ionization detector.
Flame ionization detectors are, for example, constructed to include a cylindrical case containing a burner nozzle having a cylindrical gas duct and being made of corrosion-proof material. An essentially cylindrical target electrode is disposed coaxially to the nozzle. The bottom structure of the case is provided with inlet ducts for the fuel gas, for the measuring gas as well as for air needed for combustion.
A detector as described is, for example, disclosed in German printed patent application No. 2 342 333 (published in 1974 and being based on a patent application in Great Britain, Ser. No. 39733-72 of Aug. 25, 1972). A detector of this type could, for example, be used for measuring the concentration of carbon in hydrocarbons contained in the exhaust fumes for combustion engines.
Existing and available equipment in that field of art, however, exhibits rather widely varying measuring results. In some instances, the measured values are just incorrect; also, in these and other instances, the measured values could not be reproduced. Even if the measuring gas contains just one hydrocarbon compound and none other, the measuring results were found to vary significantly. The detectors had different responses. Conceivably then, the instrument had undiscovered design flaws.